Nonreducible rotational head tilt and atlantoaxial lateral mass collapse. Clinical and roentgenographic features in patients with juvenile rheumatoid arthritis and ankylosing spondylitis.

Nonreducible rotational head tilt resulting from predominantly unilateral collapse of the lateral mass of the atlas (C1) and/or axis (C2) has been characterized in patients with rheumatoid arthritis. An identical phenomenon is reported in five patients with juvenile rheumatoid arthritis (JRA) and in six with ankylosing spondylitis (AS). Most patients had neck pain and crepitus, all had a fixed head tilt deformity, and most also had a rotational deformity. Roentgenographically, all had predominantly unilateral collapse of the lateral masses of C1 and/or C2, and the head always tilted toward the most collapsed side. The patients with JRA had polyarticular disease of long duration and generally mild neck symptoms, with only one requiring neck surgery for pain. The patients with AS tended to have proximal peripheral joint involvement and long-standing disease with more severe neck symptoms; four underwent posterior cervical fusion for intractable pain. None of the 11 patients had demonstrable neurologic deficits.